Recently, HDMI (High Definition Multimedia Interface) has been in widespread use as a communication interface for transporting at high speed a digital video signal from an AV source (Audio Visual source) such as a DVD (Digital Versatile Disc) recorder or a set top box to a display such as a television receiver or a projector. For example, the digital video signal is a non-compressed (baseband) video signal (hereinafter, referred to as “image data”) with a digital audio signal (hereinafter, referred to as “audio data”) accompanying the video signal. For example, Patent Document 1 describes in detail the HDMI standard.
FIG. 27 shows a configuration example of an AV (Audio Visual) system 5.
The AV system 5 includes a disc recorder 10 as a source apparatus and a television receiver 20 as a sink apparatus. The disc recorder 10 and the television receiver 20 are connected via an HDMI cable 61. In the disc recorder 10, an HDMI terminal 11 connected with an HDMI transmitting unit (HDMI TX) 12 is arranged. In the television receiver 20, an HDMI terminal 21 connected with an HDMI receiving unit (HDMI RX) 22 is arranged. One end of the HDMI cable 61 is connected to the HDMI terminal 11 of the disc recorder 10, and the other end of the HDMI cable 61 is connected to the HDMI terminal 21 of the television receiver 20.
In the AV system 5 shown in FIG. 27, a video signal and an audio signal reproduced in the disc recorder 10 are transmitted to the television receiver 20 via the HDMI cable 61. In the television receiver 20, image displaying and audio outputting are performed.
Content relating to a multi-channel audio is also present in the audio signal reproduced in the disc recorder 10, and thus, when the television receiver 20 is not able to decode the multi-channel audio, an audio amplifier 30, as a repeater apparatus, is connected between the disc recorder 10 and the television receiver 20 so as to solve this problem, as shown in FIG. 28.
That is, in the audio amplifier 30, an HDMI terminal 31 connected with an HDMI receiving unit (HDMI RX) 33 is arranged, and besides, an HDMI terminal 32 connected with an HDMI transmitting unit (HDMI TX) 34 is arranged. One end of the HDMI cable 61 is connected to the HDMI terminal 11 of the disc recorder 10, and the other end of the HDMI cable 61 is connected to the HDMI terminal 31 of the audio amplifier 30. Furthermore, one end of an HDMI cable 62 is connected to the HDMI terminal 32 of the audio amplifier 30, and the other end of the HDMI cable 62 is connected to the HDMI terminal 21 of the television receiver 20.
In an AV system 5A shown in FIG. 28, a video signal reproduced in the disc recorder 10 is supplied to the television receiver 20 via the HDMI cable 61, the audio amplifier 30, and the HDMI cable 62, and an image is displayed in the television receiver 20. On the other hand, an audio signal reproduced in the disc recorder 10 is supplied to the audio amplifier 30 via the HDMI cable 61, and after the audio signal is processed in the audio amplifier 30, the processed signal is supplied to an externally mounted 5.1 channel speaker group, for example, and audio is outputted in the speaker group 35.
In the case of the AV system 5A shown in FIG. 28, without taking into consideration a process delay of the video signal and the audio signal generated in the audio amplifier 30 and a process delay of the video signal and the audio signal generated in the television receiver 20, the displayed image cannot be synchronized with the outputted audio, and a disturbance of a so-called lip-sync takes place.
To synchronize the displayed image with the outputted audio, a process as shown in FIG. 29 is performed. That is, the television receiver (sink apparatus) 20 stores therein delay information (T2v=80, T2a=80) about video and audio in an internal EDID of HDMI. The audio amplifier 30 reads the delay information (T2v=80), and computes a delay time (T=T2v−T3a−T4a=30) of the displayed image with respect to an audio signal, based on delay time generated by the audio amplifier 30 (T3a=50) and delay information (T4a=20) of the disc recorder (source apparatus) 10. Thereafter, the audio amplifier 30 internally delays the audio signal by only the calculated delay time so as to synchronize the displayed image and the outputted audio.
FIG. 30 shows a data structure of Vendor Specific Data Block in a storage region of the EDID of the sink apparatus.
In data represented by “Vender Specific”, 0-th to N-th blocks, each of which is 1-byte block, are arranged.
In the 0-th block (Byte0) at a head of data represented by “Vender Specific”, information indicating a header indicating a data region of the data “Vender Specific” represented by “Vendor-Specific tag code (=3)” and information indicating a length of the data “Vender Specific” represented by “Length (=N)” are placed.
In the first block (Byte1) to the third block (Byte3), information indicating a number “0x000c03” registered for the HDMI, represented by “24 bit IEEE Registration Identifier (0x000C03) LSB first”, is placed. Further, in the fourth block (Byte4) and the fifth block (Byte5), 24-bit information indicating physical addresses of the sink apparatus, each represented by “A”, “B”, “C”, and “D”, is placed.
In the sixth block (Byte6), a flag, represented by “Supports-AI”, indicating a function which the sink apparatus supports, pieces of information, which are represented by “DC-48 bit”, “DC-36 bit”, and “DC-30 bit”, respectively, designating a bit number per pixel, a flag, represented by “DC-Y444”, indicating whether the sink apparatus supports a transport of an image of YCbCr 4:4:4, and a flag, represented by “DVI-Dual”, indicating whether the sink apparatus supports a dual DVI (Digital Visual Interface) are placed.
Also, in the seventh block (Byte7), information, represented by “Max-TMDS-Clock”, indicating a maximum frequency of a pixel clock of TMDS is placed. Further, in 2-bit MSB of the eighth block (Byte8), a flag (indicating whether or not values in the Bytes 9 to 12 are effective), represented by “Latency”, indicating presence or absence of delay information of video and audio is placed.
In the ninth block (Byte9) of the data represented by “Vender Specific”, delay-time data of progressive video, represented by “Video Latency”, is placed. In the tenth block (Byte10), delay-time data of audio accompanying the progressive video, represented by “Audio Latency”, is placed. In the 11th block (Byte11), delay-time data of interlaced video, represented by “Interlaced Video Latency”, is placed. In the 12th block (Byte12), delay-time data of the audio accompanying the interlaced video, represented by “Interlaced Audio Latency”, is placed.
Incidentally, as shown in FIG. 31, when the disc recorder 10 is connected with not only the HDMI terminal 21 connected with the HDMI receiving unit 22 but also with the television receiver 20A in which the HDMI terminal 23 connected with the HDMI receiving unit 24 is arranged, it is possible to consider a configuration that the HDMI terminal 23 of the television receiver 20A is connected with the audio amplifier 30 via the HDMI cable 62. In this case, from the television receiver 20A to the audio amplifier 30, the audio data is sent via Ethernet (not shown), for example.
In an AV system 5B shown in FIG. 31, when the aforementioned process as shown in FIG. 29 is employed, it is not possible to synchronize the displayed image and the outputted audio. That is, when computing the delay time of the audio signal with respect to the displayed image, the audio amplifier 30 needs to consider not only the delay time generated by itself, and delay information of the disc recorder (source apparatus) 10 but also a time required for processes such as encryption of the television receiver 20A for transmitting the audio signal to the audio amplifier 30.
Patent Document 2 describes a lip-sync function embodied using CEC control. Also, Patent Document 3 describes that adjustment for a delay time is performed in an apparatus inserted between a source apparatus and a sink apparatus. Furthermore, Patent Document 4 describes a delay matching, performed in a source apparatus, between a video signal and an audio signal.    [Patent Document 1] WO2002/078336    [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2006-33436    [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2006-186544    [Patent Document 4] WO2002/077825